Conventional to Syn back to Conventional

[Makdaddymac]

the rumor is that switching from conventional to syn on a high mileage engine ruins gaskets? well i have a new to me(used civic) car that the oil is fine and changed i just forgot to ask the guy if it was synthetic or not the car has high mileage on it...., and i dont want to put synthetic in it unless thats what he was using. but would switching to conventional hurt anything? i dont want oil leaks on this civic since it doesnt make a tick,leak, or smoke....... also going to put 10w40 high mileage?
or should i stick with 5w-40?

 

[Maryland Stang]

Synthetics don't ruin gaskets. They just flow easier especially when cold. They also often have better detergent packages and tend to clean things up and out when they're used. This leads to the rumor that synthetics cause leaks. They don't. They may just find one that wasn't leaking so much. You can switch back and forth as much as you like. My F-150 had about 110,000 miles on it when I tried Pennzoil Platinum. It did start using oil. About a quart every 1,500 miles. It wasn't using any before the switch. I switched it back to conventional Pennzoil 10w30 and it hasn't used any oil since.

 

[Darkwriter77]

Synthetics don't ruin gaskets. They just flow easier especially when cold. They also often have better detergent packages and tend to clean things up and out when they're used. This leads to the rumor that synthetics cause leaks. They don't. They may just find one that wasn't leaking so much. You can switch back and forth as much as you like. My F-150 had about 110,000 miles on it when I tried Pennzoil Platinum. It did start using oil. About a quart every 1,500 miles. It wasn't using any before the switch. I switched it back to conventional Pennzoil 10w30 and it hasn't used any oil since.

+1

The people telling you that you can't switch from conventional to synthetic and back are probably the same folks that believe those Tornado things add 15 horses and that pouring NOS brand octane booster in your gas makes your car run a lot faster.

 

[strtrcr50]

+1

The people telling you that you can't switch from conventional to synthetic and back are probably the same folks that believe those Tornado things add 15 horses and that pouring NOS brand octane booster in your gas makes your car run a lot faster.

You mean the tornado doesn't work?

 

[Vipersix]

Are you kidding me? The Tornado works better than advertised. Basically what happens is the air comes in and... it sorta... Well see, normally when the air comes in with a standard tube and it hits the corners... umm... There's like this cyclone thing that swirls the air which picks up extra oxygen molecules from the... uhh... other air molecules and stuff... It just works! PFM!